This invention relates to a coolant expansion tank, particularly for motor vehicle internal-combustion engines, having at least one filling chamber for receiving the coolant and at least one expansion chamber that is separated from the filling chamber by means of a partition wall.
A coolant expansion tank of this type is known from DE-OS No. 2,852,725. There, the tank, by means of a vertically arranged partition, is divided into a filling chamber and an expansion chamber. The upper area of the filling chamber, via a connecting line, is connected with the lower area of the expansion chamber. Normally, the filling chamber is filled with the coolant up to a certain level. For example, because of a high operating temperature of the internal-combustion engine to be cooled, the coolant is heated and therefore expands. This has the result that the coolant from the filling chamber, via the connecting line, overflows into the expansion chamber. In the case of a subsequent cooling of the coolant, it is, by means of a vacuum, again drawn back from the expansion chamber into the filling chamber. For the operatability of a coolant expansion tank of this type, especially for the following-back of the coolant from the expansion tank into the filling chamber by means of a vacuum, it is not only important that the exterior walls of the coolant expansion tank are tight, but also that the partition separates the expansion chamber and the filling chamber tightly from one another.
It is the objective of the invention to provide a coolant expansion tank, particularly for motor vehicle internal-combustion engines, in which simultaneously with the checking of the exterior walls of the coolant expansion tank concerning their tightness, also the partition separating the filling chamber and the expansion chamber from one another can be examined with respect to its tightness.
These and other objectives are achieved by forming the position between the filing and expansion chambers as double wall having a monitorable checking space therebetween.
This development of the partition makes possible a checking of the tightness of said partition. For checking the tightness of the coolant expansion tank, a test agent, possibly under pressure, is filled into the coolant expansion tank. If the partition is not tight, the test agent comes out in the testing space formed by two walls of the double wall. This can be determined by monitoring the testing space so that in this manner, the checked coolant expansion tank can be recognized as being leaky. Leaky points of the exterior wall of the coolant expansion tank can be determined in the same working cycle by the emerging of the testing agent at the corresponding points of the exterior valve.
In an advantageous development of the invention, the two wall of the partition are made into a testing chamber by means of transverse walls. In this way, a closed testing chamber is formed. In the case of one embodiment, the exterior walls of this testing chamber are the same dimension as the exterior walls of the adjacent filling chamber and expansion chamber.
For the monitoring of the testing chamber, in the case of a further development of the invention, at least one transverse wall has at least one opening leading to the outside. If the partition between the filling chamber and the expansion chamber is leaky, testing agent, as described above, will enter the testing chamber and go to the outside through the opening. The leakiness of the partition can therefore be recognized by the fact that testing agent emerges from the opening. It is advantageous to provide openings of this type at all exterior walls of the testing chamber so that the orientation of the coolant expansion tank is not important during its leak test.
In a further development of the invention, it is provided that between the two walls of the partition, a connecting line is arranged that connects the filling chamber and the expansion chamber with one another. Thus, the connecting line is integrated into the coolant expansion tank, which is particularly advantageous for the manufacturing and the operability of the coolant expansion tank. Also by providing the connecting line between both walls of the testing space, the tightness of the connecting line is checked simultaneously with the leak test of the coolant expansion tank and particularly of the partition. The reason is that, if the connecting line is leaky, testing agent will emerge from the connecting line into the testing space which can be determined as described above.
For the manufacturing of the coolant expansion tank, it is advantageous for the coolant expansion tank to consist of at least two housing parts that are fitted together along a parting line forming a joining plane. If, in this case, the joining plane intersects with the partition, simultaneously with the leak test of the partition, the partying line of the joining plane intersecting with the partition is also checked with respected to its tightness. Therefore, during the construction of the coolant expansion tank, attention does not have to be paid as to how the joining plane extends, for even when a parting line intersects with the partition and thus the possibility of leakiness of the partition because of a leaky parting line is increased, this type of leakiness can be determined reliably.
Another advantage of the coolant expansion tank according to the invention is the fact that the design of the filling chamber and the expansion chamber, the arrangement and development of the wall forming the testing space, the design and course of the connecting line within the testing space as well as the position of the joining plane of the two halves of the housing of the coolant expansion tank can be selected completely arbitrarily. The same is true for the method of manufacturing of the coolant expansion tank. It is particularly advantageous to construct the coolant expansion tank as an injection-molded part made of plastic.
Further objects, features, and advantages of the present invention will become more apparent from the following description when taken with the accompanying drawings which show, for purposes of illustration only, an embodiment in accordance with the present invention.